This dissertation examines how certain epidemic outbreaks become "global threats", that is, diseases that become the focus of international regulations and organized responses while others do not. To answer this question, this dissertation draws upon archival data collected at the World Health Organization (WHO) archives in Geneva, the Western Cape Archives in Cape Town, the British Library, British National Archives, the Wellcome Library Archives in London, and twelve qualitative interviews with senior global health actors in order to analyze five cases when disease threats were prioritized internationally as well as how these constructions patterned responses to outbreaks. I begin by exploring the formation of the first international disease controls in the 19th century, the International Sanitary Conventions, created to prevent the spread of three diseases- plague, cholera and yellow fever. I probe how these earliest conventions patterned responses to diseases covered under them and limited responses to those beyond their scope. Examining how these conventions transformed, I explore why the same disease priorities were maintained by the WHO in their International Sanitary Regulations of the 1950's. Finally, I analyze the transformation of the International Health Regulations in 2005 and its effects on the assessment of disease threat. This dissertation shows that three factors structure the construction of disease threat: epidemic orientalism, economic concerns and field dynamics. Epidemic Orientalism, a discourse motivating the construction of disease threat that first emerged in the 17th, 18th and 19th centuries, positioned the colonized world as the space from which Europe and the Imperial powers needed to be protected. This orientalist gaze prioritizes the control of diseases emanating from colonial sites that threaten international trade and commerce and has been re-inscribed in all past and present regulations. These factors explain how and why plague, cholera and yellow fever came to be maintained as the primary diseases of international concern until the 21st century. As the WHO has recently been challenged in its authority to manage disease threats, these two factors are also mediated by the WHO's manipulation of symbolic power within a new field of infectious disease management which conditions responses to outbreaks today.